移动端开发--参考京东（屏幕范围）

@media screen and (max- 320px) {
}
@media screen and (min- 321px) and (max- 374px) {
}
@media screen and (min- 375px) and (max- 413px) {
}
@media screen and (min- 414px) and (max- 559px) {
}
@media screen and (min- 560px) and (max- 639px) {
}
@media screen and (min- 640px) {
}